Mobile communication devices are proliferating in functions and uses, with increasing demands upon communication infrastructures to evolve to meet the demand. Mobile communication devices, also referred to as access terminals and user equipment, continue to merge in capabilities with other types of computing devices such as wireless capable laptop and notebook computers. As such, so called third- and fourth-generation mobile communication systems are moving toward essentially a wireless broadband Internet system with voice and other services built on top. Paying for such wireless communication thus needs to address data packet nature of the usage and the distributed and increasingly flatter architecture. Collecting all of the accounting tracking data in a core network can be disadvantaged in obtaining such usage data accurately and without an undue amount of message traffic.
As depicted in FIG. 1, in a conventional converged communication system 100 having Internet Protocol (IP) services provided by a core network 102, packet data accounting parameters are divided into radio specific parameters collected by a Radio Access Network (RAN) 104 that communicates with end user equipment (access terminals) 106 via an air link 107, and IP network specific parameters collected by a core network function, such as a Serving Packet Data Serving Node (PDSN) 108. The Serving PDSN 108 merges radio specific parameters in interface messages called Air link Records, depicted at 110, from the RAN 104 passed through a packet control function (PCF) 112 with IP network specific parameters to form one or more Usage Data Records (UDR) in accordance with prepaid rules 114 or charging rules 116. Prepaid packet data service allows a user to purchase packet data service in advance based on volume or duration.
After merging the air link records 110, the Serving PDSN 108 uses accounting messages (e.g., RADIUS accounting protocol) to send UDR information, depicted at 118, to a Authentication, Authorization and Accounting (AAA) server 120, which can entail a visited AAA server communicating with a home AAA server, perhaps with a proxy AAA server interfacing there between, for example. The serving PDSN 108 maintains accumulated UDR information until the packet data service is terminated or until the server PDSN 108 receives positive acknowledgment from the AAA server 120 that the AAA server 120 has correctly received the UDR message. For instances in which the AAA server 120 is a visited rather than a home AAA server, the visited AAA server 120 maintains the UDR until the record is delivered to a home AAA server (not shown), or removed by an operator billing system (not shown).
The Packet Data Serving Node, or PDSN, is a component of a CDMA2000 mobile network. It acts as the connection point between the Radio Access and IP networks. This component is responsible for managing point-to-point protocol (PPP) sessions between the mobile provider's core IP network and the mobile station (read mobile phone). The PDSN also provides packet filtering functions and provides QoS connection for IP flows with Access Network. It is similar in function to the GGSN (GPRS Gateway Support Node) that is found in GSM and UMTS networks. The PDSN can be thought of being similar to GGSN in a conceptual sense. Logically, it can also be considered to be a combination of Serving GPRS Support Node (SGSN) and GGSN in the CDMA world. The PDSN provides: (a) Mobility management functions (provided by SGSN in the GPRS/UMTS networks); and (b) Packet routing functionality (provided by GGSN in the GPRS/UMTS networks).
Challenges exist in that the serving PDSN 108 is significantly removed from the communication chain to the access terminal 106. Challenges also exist in that some IP functions of PDSN108 is moved to the radio access network (104) such as packet filtering functions and QoS control function. The usage data of data sent over the air (OTA) 122 that the RAN 104 can monitor is more accurate as compared to data 124 that is often received by the PDSN 108. The conventional PDSN accounting architecture presents issues with regard to accounting accuracy. On forward link with the PDSN counting packets, the data is not sent from the base station to the mobile station due to over-the-air resource constraints, and thus the accounting is inaccurate. In the reverse link, if the data is received from the mobile station to the base station and if the data is lost on backhaul, the reserve data will not be counted by the PDSN even through the air interface has consumed resources.